Location requests and measurement responses in wireless communications networks and methods

ABSTRACT

A method for requesting location information, for example, Enhanced Observed Time of Arrival timing information, from mobile wireless communications in wireless communications networks. The exemplary location request ( 300 ) includes multiple response interval field ( 310 ) specifying intervals at which multiple responses to the location request must be sent or maximum intervals between which multiple responses to the location request must be sent, a final response time field ( 320 ) specifying a maximum time interval during which a final response to the location request must be sent, and an initial response time field ( 330 ) specifying when an initial response to the location request must be sent.

FIELD OF THE DISCLOSURE

[0001] The present disclosure relates generally to wirelesscommunications, and more particularly to location requests andresponses, for example, network originated Enhanced Observed TimeDifference (E-OTD) location requests and subscriber device E-OTDmeasurement responses, in wireless communications networks and methodstherefor.

BACKGROUND OF THE DISCLOSURE

[0002] Some Enhanced Observed Time Difference (E-OTD) locationtechnology architectures initiate E-OTD measurements in cellularsubscriber devices by sending a location request from wirelesscommunications networks to subscriber devices. For example, networkrequests for location information from subscriber devices are madeduring E-911 calls initiated by subscriber devices, and in response toinquiries from subscriber devices for location-based services.

[0003] E-OTD location requests from networks typically include a list ofassistance cells from which a subscriber device must attempt to obtaintiming measurements. The assistance cell list is generally differentfrom the list of neighbor cells monitored by the subscriber device forhandover procedures.

[0004] Generally, the greater the number of cells on which measurementsare made by the subscriber device in response to a location request, thebetter the accuracy of the location computation. However, the networkmust provide the subscriber device with a relatively short list ofassistance cells, since the subscriber device must respond to thelocation request within a specified time period. Thus it is desirablefor the network to accurately identify assistance cells on which thesubscriber device will most likely obtain measurement data. Presently,the network selects the assistance cells based on a rough locationestimate of the subscriber device. The rough location estimation isderived generally from timing advance and from sector or cellidentification information.

[0005] Also, presently, networks must specify a response time withoutany knowledge of the radio conditions experienced by the subscriberdevice to which the location request is sent. Propagation delay of thenetwork location request through the network is significant relative tothe time period during which the subscriber device must perform therequested timing measurements. Similarly, the time required for themeasurement information response to propagate from the subscriber deviceback to the network location server is not insignificant. Thepropagation delay generally increases the time required to locate thesubscriber device.

[0006] Upon receipt of a response from a subscriber device, the networkmust determine the position of the subscriber device using measurementdata from a single response of the subscriber device, since the networkaccepts only a single subscriber device response to the network locationrequest. Thus the network computes the location of the subscriber devicebased upon assumptions, which may be inaccurate, and without anyindication of E-OTD measurement trends.

[0007] The various aspects, features and advantages of the presentdisclosure will become more fully apparent to those having ordinaryskill in the art upon careful consideration of the following DetailedDescription and the accompanying drawings described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is an exemplary wireless communications network.

[0009]FIG. 2 is an exemplary process flow diagram for sending multipleresponses in reply to a location request.

[0010]FIG. 3 is an exemplary network location request message.

[0011]FIG. 4 is an exemplary process flow diagram for obtaining multiplemeasurements on one or more signals and sending a response based uponthe multiple measurements.

[0012]FIG. 5 is an exemplary process flow diagram for sending multiplemeasurement information sets in response to a location request.

DETAILED DESCRIPTION

[0013]FIG. 1 illustrates an exemplary wireless communications network inthe form of a Global System For Mobile communications (GSM) network 100supporting wireless communications for mobile wireless communicationdevices, for example, mobile station (MS) 110, also referred to hereinas a mobile wireless communications device or as user equipment.

[0014] The mobile wireless communications device may be a wirelesscellular telephone, or a two-way pager, or a wireless enabled personaldigital assistant (PDA) or notebook or laptop computer, or some otherradio communications device, anyone of which may be a cellularcommunications service subscriber device, or subscriber terminal.

[0015] The exemplary network 100 comprises generally a plurality ofbase-station transceivers (BTS) 120 that communicate with a base stationcontroller (BSC) 130, which communicates with a Serving Mobile LocationCenter (SMLC) 140, a Mobile Switching Center/Visitor Location Register(MSC/LVR) 150 and a Cell Broadcast Controller (CBC) 160. The BSC andMSC/LVR are communicably coupled to a Serving GPRS Switching Node (SGSN)170. The MSC/LVR is communicably coupled to the SMLC 140, a Gateway MLC(GMLC) 180 to GMLCs in other Public Land Mobile Networks (PLMNs), forexample, PLMN 190. In FIG. 1, the gateway MLC 180 is coupled to a HomeLocation Register (HLR) 185, to a GSMSCF 187, and to an externalLocation Services (LCS) Client 195, for example, an E-911 operator.These and other aspects of GSM and other communications networkarchitectures are known generally.

[0016] The exemplary GSM network 100 includes a plurality LocationMeasurement Units (LMUs) 197 which may be co-located at the BTSs or atother locations in the network for supporting Enhanced Observed TimeDifference (E-OTD) GSM Location Services (LCS) and possibly otherlocation technologies. The exemplary GSM communications network may alsosupport other location services as specified, for example, in GSM 04.35,Broadcast Network Assistance For E-OTD and Global Positioning System(GPS) Methods.

[0017] Generally, location Services (LCS) architectures compute locationeither at the network or at the mobile station. In MS-assisted LCSarchitectures, location is determined at the network, for example, atthe SMLC, with information received from the mobile station. In MS-basedlocation architectures, location is computed at the mobile station, withor without information received from the network. The mobile stationlocation fix or information is then communicated to the requestor orother destination. Location requests may originate from within thenetwork, for example, from a network location server, like an SMLC orfrom an external client, for example, from E-911 centers, indicated asLCS Client 195 in FIG. 1.

[0018] The GSM communications network architecture of FIG. 1 is onlyexemplary and not intended to limit the invention. The inventions applymore generally to all communications networks that provide or supportlocation services, including, for example, 3rd Generation (3G) UniversalTerrestrial Radio Access Network (UTRAN), 4th Generation communicationsnetworks and among other existing and future communications network andsystems. These and other networks may support E-OTD and other locationservices including, for example, Global Positioning System (GPS) andother satellite positioning system location services, as well networkbased location services, for example, Time of Arrival (TOA), TimeDifference of Arrival (TDOA) among other location determination schemes,including fused location schemes, or combinations thereof.

[0019] In the exemplary process flow diagram 200 of FIG. 2, at block210, according to one aspect of the disclosure, a mobile stationreceives a location request from a network. The location request may begenerated in response to an E-911 call initiated by the mobile station,although in other applications the location request may be prompted bysome other inquiry from the mobile station, for example, in response toa request by the mobile station for location-based services.Alternatively, the location request may originate from the network, forexample, the request may be initiated by an application or by a thirdparty trying to locate the mobile station.

[0020] In some applications, the network location request is formeasurement information obtained or processed by the mobile station. Thenetwork, for example, a network location server, may use the measurementinformation to compute the location of the mobile station. In someapplications, the mobile station sends a response based upon measurementinformation to the network without processing the information. In otherapplications, the mobile station processes the measurement informationbefore sending the response to the network. The mobile station may, forexample, average measurements, or compute one or more pseudorangesbetween the mobile station and one or more corresponding signal sources,or the mobile station may compute its location fix. The response to thelocation request may thus be based upon partially or completelyprocessed measurement information, or it may be unprocessed measurementinformation.

[0021] The mobile stations generally obtain measurement information fromone or more signals transmitted from corresponding signal sources, forexample, from corresponding cellular base stations and other terrestrialsources, and from non-terrestrial sources including space vehicles insatellite positioning and communications systems. Exemplary measurementinformation includes Enhanced Observed Time Difference (E-OTD) timinginformation, Time of Arrival (TOA) information, Time Difference ofArrival (TDOA) information, and pseudorange measurements based uponsignals transmitted from corresponding space vehicles of a satellitepositioning system or other signal sources, among other information.

[0022] In FIG. 2, at block 220, the mobile station sends a response tothe network location request. In some applications, the mobile stationsends multiple responses, for example, at least two responses, to thenetwork in response to the network location request. In otherapplications, however only a single response is sent to the network. Insome instances, for example, only a single response is required. Inother instances, the network sends a new or updated location requestbefore the mobile station sends more than one response to the firstlocation request, as discussed more fully below.

[0023] In some applications, the response is based upon measurementinformation obtained from one or more signal sources. For example, theresponse maybe based upon multiple measurements made on a signal from asingle source. Alternatively, the response may be based upon multiplemeasurements made on multiple signals from corresponding signal sources,examples of which are discussed more fully below.

[0024] In some applications, the first response to the location requestis preliminary response based upon information obtained by the mobilestation prior to receipt of the location request or based uponinformation obtained after the location request is received. In someembodiments, the preliminary response is based upon measurementinformation obtained from or on signals from sources other than thosespecified in the location request, for example, on cells other thanthose identified in a location assistance cell list provided in thelocation request.

[0025] In other applications, the preliminary response is based uponrough timing information, for example, on ¼ bit handover timingmeasurements obtained from cells or other signal sources to which themobile station is synchronized for handovers. In other embodiments, thepreliminary response includes a mobile station location fix obtained byor computed at the mobile station, for example, a location fix computedprior to receipt of the location request. In other embodiments, thefirst response is based upon information obtained from signal sourcesspecified in the location request. Responses based upon informationobtained by the mobile station prior to receipt of the location requestmay be sent immediately upon receipt of the request.

[0026] In FIG. 2, at block 230, in applications where the networklocation request specifies sources from which information is to beobtained by the mobile station, the network may send an updated list ofsignal sources from which to obtain measurement information based uponthe preliminary response. In some embodiments, the updated list is sentas part of a new or updated location request. In other embodiments theupdated list does not include a new request.

[0027] In FIG. 2, at block 240, in embodiments where the mobile stationsends multiple responses to the location request, the mobile stationsends a subsequent response. In applications where the network does notsend an updated signal source list, the next response referenced atblock 240 may be based upon a signal source list provided in the initiallocation request.

[0028] In applications where the mobile station receives an updatedsignal source list from the network, the next response from the mobilestation, referenced at block 240, may or may not be based uponmeasurement information obtained using the updated signal source list.For example, upon receipt of an updated list, the mobile station maybegin taking new measurements on signal sources in the new list anddisregard previous measurements. Alternatively, if the mobile stationhas nearly completed obtaining information for inclusion in the nextresponse when the updated signal source list arrives, the mobile stationmay disregard the new signal source list until after sending the nextresponse.

[0029] In embodiments where the response at block 220 is based upon ameasurement information set, the response at block 240 is also likelybased upon a measurement information set, although the responses atblocks 220 and 240 may have been made on different signal sources.

[0030] In some embodiments, the mobile station sends multiple responsesto the network in response to a command or instruction in the networklocation request for multiple responses. In one embodiment, the locationrequest includes a multiple response command field, which instructs themobile station to send multiple responses to the location request. Therequest may indicate that the network accepts multiple responses sent bythe mobile station, or it may indicate the multiple responses aremandatory. Also, the request may specify how many responses the mobilestation may or must send to the network. The request may also provide atemporal framework for when the responses should be sent.

[0031] In FIG. 3, an exemplary location request message includes amultiple response time interval field 310 specifying the time period orthe maximum time period that may lapse between communicating multipleresponses from the mobile station in response to a location request. Inone exemplary embodiment, suitable for E-OTD measurement locationrequest applications, the multiple response time interval is specifiedin seconds represented by 2^(N), where N is the value of the field,e.g., N=0, 1, 2, 3, etc. Exemplary intervals are 1, 2, 4, or 8 seconds.

[0032] In FIG. 3, the location request also includes preferably a finalresponse time field 320 specifying the maximum time that may elapsebefore sending the last or final response. In one exemplary embodiment,suitable for E-OTD measurement location request applications, the finalresponse time is specified in seconds represented by 2^(N), where N isthe value of the field, e.g., N=0, 1, 2, 3, etc. Exemplary finalresponse times are 1, 2, 4, 8, 16, 32, 64, or 128 seconds. The finalresponse time field may be included in embodiments where the networklocation request includes a multiple response time interval field.

[0033] In some embodiments, the request includes a response time, withinwhich at least one response from the mobile station must be sent. Thusin embodiments, where the network accepts multiple responses, the mobilestation must send multiple responses before the response time specifiedin the location request.

[0034] In FIG. 2, at block 250, a final response is sent from the mobilestation to the network within a response time, or within a finalresponse time, specified in the location request. Also, generally, thenetwork may send the mobile station an updated signal source list fromwhich it prefers that the mobile station obtain measurement information,for example, an updated assistance cell list in E-OTD applications. Theupdated signal source list may be based upon any one or more of themultiple responses received from the mobile station, for example, basedupon the response at blocks 220 or 240 in FIG. 2. As discussed, theupdated signal source list may be standalone information or it may bepackaged with an updated location request or other information.

[0035] In some applications, the mobile station includes an indicationthat a response is a final response, for example, where multipleresponse are sent in reply to a location request.

[0036] In FIG. 3, in some embodiments, the network location requestincludes an initial response time field 330 specifying the maximum timethat may elapse before the mobile station sends the initial or firstresponse, foe example, where multiple responses are accepted orrequired. In one embodiment, the initial response filed may be set witha “0” or a “1” bit. A “0” bit may indicate that a response must be sentimmediately upon receipt of the location request. For an immediateresponse, the mobile station may send a preliminary response based, forexample, upon rough timing information obtained for handover purposes,or based on other preliminary information including locationcomputations. A “1” bit may indicate that the maximum response time issome other value, for example, the value of a multiple response timeinterval divided by the number of intervals specified.

[0037] In the process flow diagram 400 of FIG. 4, at block 410,measurement information is obtained by taking multiple measurements onone or more signal sources, for example, the acquisition of E-OTD timingand other information from corresponding signal sources. In one mode ofoperation, at block 420, multiple signal measurements are made on theone or more signals, and at block 430 the measurement information usedto formulate at least a partial response to the location request uponsatisfying a condition. In one embodiment, the response is at leastpartially formulated when a variance of the multiple measurementssatisfies a condition. In another embodiment, the response is at leastpartially formulated when a rate of change of standard deviation of themultiple measurements on the signal satisfies a condition. The conditionmay be a threshold, determined based upon empirical data or otherinformation. At block 440, a response based upon the measurementinformation is sent to the network.

[0038] In one embodiment, the mobile station obtains measurementinformation by taking multiple measurements on a plurality of at leasttwo signals from corresponding signal sources. A response, based on theplurality of signal measurements, is sent in reply to the locationrequest when a variance of multiple measurements on each of theplurality of signals satisfies a condition or when a rate of change ofstandard deviation of multiple measurements on each of the plurality ofsignals satisfies a condition.

[0039] In one embodiment, the mobile station includes multiplemeasurements information sets in a response to a location request,wherein each measurement information set is based on measurementinformation obtained from multiple signal sources. In one embodiment,the mobile station formulates a measurement information set when thevariance or rate of change of standard deviation of multiplemeasurements on each of the signals measured satisfies a condition.Alternatively, a measurement information set may be formulated uponobtaining a specified number of acceptable measurements on each signalmeasured. Generally several measurement information sets are formulated,from measurements made on multiple signals, and stored prior totransmission in the response.

[0040] In FIG. 5, at block 510, the mobile station receives a locationrequest specifying that the response provide a plurality of at least twomeasurement information sets. At block 520, the mobile station obtainsmeasurement information, for example, E-OTD timing information orpseudorange information, etc. At block 530, a response is formulatedhaving multiple information sets based upon the measurement information.At block 540, the mobile station sends the response based upon orincluding the measurement information sets obtained or formulated.

[0041] In FIG. 3, the location request 300 include a field 340 thatspecifies the minimum number of measurement information sets that mustbe sent in each response. In some embodiments, the number of sets fieldis inapplicable to the first response in application requiring multipleresponses, for example, where an immediate first response is requested.In one exemplary embodiment, the minimum number of sets field is N+2,where N is the value of the field having an exemplary range between 0and 1.

[0042] In some embodiments, the location request specifies measurementinformation set interval information, for example, the maximum timeinterval that may elapse between measurement information sets. In theseembodiments, preferably, the mobile station must obtain measurementinformation sets at intervals not later than the intervals specified inthe network location request. In FIG. 3, the field 340 may alternativelyspecifies the measurement information set interval without or withoutspecifying the number of measurement information set required.

[0043] While the present disclosure and what is considered presently tobe the best mode or modes thereof have been described sufficiently toestablish possession by the inventors and to enable those of ordinaryskill to make and use the inventions, it will be understood andappreciated that there are equivalents to the exemplary embodimentsdisclosed herein and that many modifications and variations may be madethereto without departing from the scope and spirit of the inventions,which are to be limited not by the exemplary embodiments but by theclaims appended hereto.

What is claimed is:
 1. A method in a mobile wireless communicationsdevice, the method comprising: receiving a network location request atthe mobile wireless communications device; sending multiple responses tothe same network location request, the multiple responses sent from themobile wireless communications device.
 2. The method of claim 1, thenetwork location request is for Enhanced Observed Time Difference(E-OTD) measurement information, sending multiple responses to thenetwork location request includes sending at least two responses, eachresponse including measurement information for a plurality of cells. 3.The method of claim 1, obtaining multiple measurement information sets,each measurement information set including measurements on a pluralityof terrestrial signal sources, sending multiple responses to the samenetwork location request includes sending the multiple measurementinformation sets.
 4. The method of claim 3, sending multiple measurementinformation sets in a single response to the network location request.5. The method of claim 3, completing each of the multiple measurementinformation sets when a variance of multiple measurements on each of theplurality of terrestrial signal sources satisfies a condition.
 6. Themethod of claim 3, completing each of the multiple measurementinformation sets when a rate of change of standard deviation of multiplemeasurements on each of the plurality signal sources satisfies acondition.
 7. The method of claim 1, sending multiple responses inresponse to a request for multiple responses in the network locationrequest.
 8. The method of claim 1, sending multiple responses atresponse intervals specified in the network location request.
 9. Themethod of claim 1, each response including measurement information for aplurality of signal sources, sending each response when a variance ofmultiple measurements on each signal source of the plurality of signalsources satisfies a condition.
 10. The method of claim 1, each responseincluding measurement information for a plurality of signal sources,sending each response when a rate of change of standard deviation ofmultiple measurements on each signal source of the plurality of signalsources satisfies a condition.
 11. The method of claim 1, the networklocation request includes a response time, sending a preliminaryresponse to the network location request, the preliminary response sentbefore the response time specified in the network location request;sending another response after the preliminary response not later thanthe response time specified in the network location request.
 12. Themethod of claim 11, receiving an updated signal source list based uponthe preliminary response sent in response to the network locationrequest.
 13. The method of claim 11, sending the preliminary response tothe network location request includes sending rough timing informationobtained from signal sources to which the mobile wireless communicationsdevice is synchronized for handovers.
 14. The method of claim 1, thenetwork location request including final response time information;sending a final response not later than a final response time specifiedin the network location request.
 15. The method of claim 1, the networklocation request including initial response time information; sending aninitial response not later than an initial response time specified inthe network location request.
 16. The method of claim 1, sending aresponse with an indication that the response is a final response sentin response to the location request.
 17. A method in a mobile wirelesscommunications device, the method comprising: receiving a networklocation request at the mobile wireless communications device; measuringa signal; sending a response, based on the signal measurement, to thenetwork location request after the occurrence of at least one of avariance of multiple measurements on the signal satisfies a condition,and a rate of change of standard deviation of multiple measurements onthe signal satisfies a condition.
 18. The method of claim 17, measuringa plurality of at least two signals from corresponding signal sources,sending a response, based on the plurality of signal measurements, tothe network location request when at least one of a variance and a rateof change of standard deviation of multiple measurements on each of theplurality of signals satisfies a condition.
 19. A method in a mobilewireless communications device, the method comprising: receiving alocation request at the mobile wireless communications device, thelocation request including measurement information set intervalinformation; obtaining measurement information sets at intervals notlater than measurement information set intervals specified in thenetwork location request; sending a response based on at least twomeasurement information sets obtained.
 20. A location request messagefor requesting location information from mobile wireless communicationsin wireless communications networks, the location request messagecomprising: a multiple response interval field, the multiple responseinterval field for specifying at least one of intervals at whichmultiple responses to the location request must be sent, and maximumintervals between which multiple responses to the location request mustbe sent.
 21. The location request message of claim 20, furthercomprising a final response time field for specifying a maximum timeinterval during which a final response to the location request must besent.
 22. The location request message of claim 20, further comprisingan initial response time field for specifying when an initial responseto the location request must be sent.
 23. The location request messageof claim 20 is a location request for Enhanced Observed Time of Arrivaltiming information including an assistance cell list from which timinginformation should be obtained.